Highly Efficient Multi-busbar Solar Cells with Ag Nano-particle Front Side Metallization

The main target for a commercially successful solar cell production is to decrease the cost/Watt-peak ratio. In the last years new techniques like fine line screen printing or plating of the front electrode entered the market. These new techniques enable a reduction of Ag or Ag containing paste of the front grid or even a substitution of this metal. Cu is a suited candidate because of its high conductivity and low price. But one should always keep in mind its high diffusivity and the associated risk of shunting the space charge region of the semiconductor device. In this work an advanced cell design with 15 round wires instead of the widely used 3-busbars and an Ag plated front metal grid is presented, leading to efficiencies of up to 19.6% for large area p-type Cz silicon solar cells with full Al BSF. This advanced cell design combines high efficiencies and low Ag consumption not only on cell, but also on module level. In addition, the Ag rear side pads which are essential for cell interconnection should be replaced by direct Sn deposition on the screen printed Al rear side. Hereby the amount of Ag needed for the solar cell metallization could be further reduced.